Study On The Energy Efficiency Design Index Optimization Of Ultra-large Container Ship Based On Prestator

Naval Architecture and shipping industry are important industries for transportation,but their increase in energy consumption and carbon emission far exceed other industries.Specially,container ships' carbon emission is the highest compared to other two main ship types and their dead weight tonnage is also increasing rapidly year by year.Therefore,it is significant to enhance the design of container ships for coping with global warming challenges in terms of energy consumption.This thesis mainly focuses on the optimization of an ultra-large container ship(10000TEU)model lines on reducing the resistance during constant speed navigation in the period of original design,which will result in the reduction of demand for engine's power and thus lower the oil consumption.Shifting method and radial basis functions method are adopted simultaneously to reconstruct the curved surface of the ship's hull.The wave resistance is evaluated based on the nonlinear Rankine source theory.And the effects on the boundary layer attached upon the hull have already been taken into consideration due to ship's shape changing during optimization by calculating the frictional resistance through the boundary layer momentum integral.The viscosity resistance,however,is calculated based on the RANS equations.The validation of the total resistance prediction accuracy is carried out by ship model resistance test.Then the best ship shape is explored in the design space subjected to the constraint of displacement by combining NSGA-II method with NLPQL method and the Kriging surrogate model is utilized to approximate the object function to improve the optimization efficiency.Finally,the energy saving device able to improve stern flow are added to the hull of the best shape in order to increase the propulsive efficiency.The numerical simulation results indicate that the optimal ship derived from this method gains significant optimization amplitude of wave resistance and marked reduction of EEDI with the addition of energy saving devices.The results also show that this optimal ship satisfy the present obligatory demands required by IMO towards newly-made container ships with consideration of the reduction factor in the first period.